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Old 07-06-2012, 09:59   #16
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Re: can you make a steel or aluminum cat? or tri?

Aluminum is good. The boat should be expertly built/welded and well maintained though. Not as forgiving as Fiberglass. When I ran the alum boat shop our boats were no heavier than a Sea Ray of similar size, and way overbuilt.
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Old 07-06-2012, 10:09   #17
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Re: can you make a steel or aluminum cat? or tri?

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Originally Posted by HapaPops View Post
I read something on this awhile back - the engineer basically said Aluminum is wonderful, strong and light - but- below a certain size (I seem to remember 50') the weight ends up too high as you need a certain plate thickness in order to get good welds.

You also have to think about a chine boat - which isn't a real issue, but many folks don't like the look. Resale value would also be a concern.

David Vann ignored engineers and NAs - he's lucky he made it as far as santa cruz.
Maybe that engineer should check with the aviation industry as to what is possible and not....
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Old 07-06-2012, 10:17   #18
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Re: can you make a steel or aluminum cat? or tri?

Theere is some truth to the minimum hull plate thickness issue. too thin and you end up with oil canning all over. What's heavier? glass or Aluminum? I'm not sure but glass is pretty heavy. 3/16 alum is doable for the hull... properly designed and welded. 5/32 possible. 1/8 iffy....
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Old 07-06-2012, 11:37   #19
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Why don't I add another metal to this, titanium, and anything else that might make a good boat hull, regardless of price. Mono or multi. Prefably multi though.
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Old 07-06-2012, 14:31   #20
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Re: can you make a steel or aluminum cat? or tri?

Russian nuke subs are made of titanium, maybe you can pick one of those up. You said regardless of price.
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Old 07-06-2012, 19:22   #21
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Quote:
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Russian nuke subs are made of titanium, maybe you can pick one of those up. You said regardless of price.
Uuuhhhh
0o
___ I'm being serious.
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Old 07-06-2012, 19:24   #22
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Re: can you make a steel or aluminum cat? or tri?

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Maybe that engineer should check with the aviation industry as to what is possible and not....
That "engineer" is Gregor Tarjan and the quote is in his book. He says that under 50' the metal is just too thick so FG boats are lighter and less expensive I expect. Over 50' and it evens out.
There was a thread where the OP only wanted an aluminum boat. He was a noobie. I pointed out that these account for only about .1% of all multis or something like that. It's probably less. Yapluka used to make alu boats but they went under. Prometa still does and they built the famous Banana boat in which a french sailor by the name of Antoine has lived on and made a living by making travel films, dvds, books etc. He is only known to the french and/or multi people. He makes a good case for an under 50' boat in alu and he paints it in water based paint. I expect it's still on the heavy side.
So, I wouldn't put too much emphasis on alu because it's just too rare.
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Old 07-06-2012, 19:32   #23
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Re: can you make a steel or aluminum cat? or tri?

And.......Titanium is about 11 bucks a pound and alu is around a buck. Titanium is an incridibly difficult metal to work with, super high melting point, super hard, and likes too be forged in a pressure furnace too I think. That's like a pressure cooker but for molten metal. Just go down to Home Depot and buy that tool.
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Old 07-06-2012, 19:34   #24
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Re: can you make a steel or aluminum cat? or tri?

Lt.
You've gone from asking about ferro cement multihulls to steel and alum. Look at Boats for Sale, New and Used Boats and Yachts - YachtWorld.com and research all the catamarans listed, you'll see what's available at what cost and build material.
You'll find no ferro cement and no titanium but you'll learn what is available and possible.
Yes, aluminum multihulls are built, any idea the cost of titanium?
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Old 07-06-2012, 22:49   #25
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Re: can you make a steel or aluminum cat? or tri?

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Originally Posted by Sand crab View Post
That "engineer" is Gregor Tarjan and the quote is in his book. He says that under 50' the metal is just too thick so FG boats are lighter and less expensive I expect. Over 50' and it evens out.
There was a thread where the OP only wanted an aluminum boat. He was a noobie. I pointed out that these account for only about .1% of all multis or something like that. It's probably less. Yapluka used to make alu boats but they went under. Prometa still does and they built the famous Banana boat in which a french sailor by the name of Antoine has lived on and made a living by making travel films, dvds, books etc. He is only known to the french and/or multi people. He makes a good case for an under 50' boat in alu and he paints it in water based paint. I expect it's still on the heavy side.
So, I wouldn't put too much emphasis on alu because it's just too rare.
Its in my interest to push FRP, because that its what we make, but the reality is that there are many great 13-15 meter Aluminium (that alyou - min - i -um) cats around and I have sailed on a number.

Like the one in the photo.

Mr Tarjan is a knowledgable chap, but I disagree with his 5o foot stipulation. I have sailed a Peter Kerr/Lizard Yachts 43 footer and it was one of the best cruising multis I have been on. It weighed in lighter than a Lagoon 400 or a FP 44 for example. Some of Tim Mumbys 48 footers have won races in SE Asia with all the cruising comforts.

If I was to build it would probably be in aluminium
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Old 07-06-2012, 23:37   #26
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Re: can you make a steel or aluminum cat? or tri?

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Old 08-06-2012, 00:06   #27
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Re: can you make a steel or aluminum cat? or tri?

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Old 08-06-2012, 12:59   #28
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Re: can you make a steel or aluminum cat? or tri?

Quote:
Originally Posted by Sand crab View Post
That "engineer" is Gregor Tarjan and the quote is in his book. He says that under 50' the metal is just too thick so FG boats are lighter and less expensive I expect. Over 50' and it evens out.
There was a thread where the OP only wanted an aluminum boat. He was a noobie. I pointed out that these account for only about .1% of all multis or something like that. It's probably less. Yapluka used to make alu boats but they went under. Prometa still does and they built the famous Banana boat in which a french sailor by the name of Antoine has lived on and made a living by making travel films, dvds, books etc. He is only known to the french and/or multi people. He makes a good case for an under 50' boat in alu and he paints it in water based paint. I expect it's still on the heavy side.
So, I wouldn't put too much emphasis on alu because it's just too rare.
Well...like a lot of Tom, Dick and Harry's of the world who self proclaim to be an expert and write a few books (to make money).....he's flat out wrong.

There are numerous boats out there of both metals well under 50 feet that are cruisin' just fine. Want to see oil canning? Look at a lot of coastal patrol boats of different governments.

Some are almost new and being scrapped...others are 40+ years old and going strong. Depends...as I and others have said....do it right and it's fine...do it wrong and pay the piper.

Maybe he's one of those engineers without the skills to design a metal boat under 50 feet or just feels that' it's better to do it in FRP...and that's OK...but doesn't mean it's not possible bcause there are plenty of boats out there proving him wrong.
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Old 08-06-2012, 13:55   #29
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Re: can you make a steel or aluminum cat? or tri?

I'm just quoting Tarjan.
Here's his bio and his site. Sailing Catamarans | Fountaine Pajot Catamarans | Power Catamarans | Multihull Dealer Brokerage
This is a multihull thread so if the other metal you are referring to is steel it doesn't apply here.

Gregor Tarjans 25 year professional background include his active involvement in the 1986 “Stars and Stripes” America’s Cup campaign, a USCG-100 Ton Masters License, a degree in Yacht Design and Art History, which all contribute in providing exceptional service to clients. He is a US Merchant Marine officer, has owned numerous large catamarans and trimarans and has participated in the Olympic Star Class, North American Championships. Gregor is fluent in German and French and his passion and theoretical knowledge of cruising multihulls can only be matched by his 30 years of practical experience sailing them across the oceans. He has performed multiple transatlantic crossings and has sailed all types of catamarans from 20-120′ in the most diverse waters from the North Sea, South Atlantic to the alpine lakes of Nepal. He is co-author of the SAILORS MULTIHULL GUIDE, writer of numerous articles for MULTIHULL, SAIL and CRUISING magazines.
Gregor Tarjan’s is considered a leading multihull expert and has published 3 important reference books:
Catamarans, Every Sailors Guide” (photos by Gilles Martin Raget) was first published in July 2006. Because of its success Mc Graw Hill Publishers, New York purchased the rights to the book and have reprinted it several times under the title
Catamarans, the Complete Guide for Cruising Sailors
In 2009 Gregor Tarjan self-published his 3rd reference book on multihulls:
Catamarans, Tomorrow’s Superyachts“. (photos by Billy Black) It is the first publication of its type and deals with the subject of large catamarans.
Gregor Tarjan is a certified, New York State licensed Yacht Broker a member of SNAME (Society of Naval Architects and Marine Engineers) and YBAA (Yacht Brokers Association of America).
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Old 08-06-2012, 14:00   #30
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I agree, there are 2 boats on yacht world right now, aluminium (uh-loo-mi-num) and under 50 feet, an one is over ten yrs old.
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